There is a lot of Rainbow Dash merchandise, but I've met more Fluttershy and Ditzy Doo/Bubbles/etc fans than Rainbow Dash fans. I do think she's merchandised more because she's not only extremely colorful, but she's also said some of the more quoted lines (like "20% cooler")

Pillow Talk.
Her name makes me snicker every time.

I liked the meaning, and figured it fit considering the kind of forum I was joining (it means 'an object of adoration' or something along those lines).
Plus, I like neat words.